Telephone-exchange system.



PATBNTED MAR. 27, 1906.

H. G. WEBSTER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEG. 3 1903.

HAPPY B. BY I W Z UNITED STATES PATENT oFFron- W Bl EEQ CHIQAGQl LIN A SIG- Q O T MBE i CARLSONW TELEPHONE MANUFACTURING COMPANY, ROCHESTER,

NEW YORK, A CORPORATION OF NEW YORK.

" rELEHbNEXdH/SNGE s-YsrEM.

lira; 816,0521

Specification oi Letters Patent. iiii iiicaiitfi fi'ieii'li'ebmbe'rls. 1903'. Serial m; 183,655

Patented lliareh 2 7, 1906.

it Wl' fl fitli WE I M he; iied smes, residfing' mobis g,

l the ountyofOook and State of I11imp shave' v med w w nn w an u l. mp eme flT ph6nq-Ei c n sy of w; chj th renewing s 2-, e111, el'eai concise, ,enjd" exabt deseriptibn,,referenoe be 5' ing h'ei'd to the ccemp nyin drawingsform iiig a,pertofthisspecificetion. v iii-My i e ion lr t .e 'v ,wt l i n T-. Q i g kii se d' fi e tempert the iiii rf sr'y is' m in sy tem s h dl in doi nectmn vyit the-mea s; for nter onneee h 1 il I b i2 i line th up vi i y g i ng isys servi g-tqiigt th medt of the operative, condition of t r H, ii i ip e l r y a p icab o, mult i -swifhb a d-e ch ge sy te i w ch pe s r q n l ii apr e i lmp b fidt pl lh s' 9f i tyi 'telepg one-line for conversational pur; fin h a" e rd1fi bmiotiii f app at twp qgrdtrands connecting Inits pre; 1 iidppl di d ld frn efi a t e ch l is p oy di 'Q Ihziiirpe 01fs i ily iig't k ng df gr supervisory si' nal may ta e the form or a" sing I, e'lect'rie Y A nofwh'ich may-mdica'te' trel st'ationf operator that the cone e i'sjno longer desired forlconversai L urpos'es, whereupon it maybe discon- 1 'j d a .AT-i ef m e m .o up vis s i'gnalingjsystem is one 'in'which a lamp is emf ploy dfore'aeh plug 1 f th 'cford circuifiwherey the; op'e1'-a;t1fiv'e; condition q'f both of two, t'dflinesmeyb a certained; I Such a tliet exchtngs. s5 b1 ,iT e 1 e-91 Ol g m '0 o r signal mpi ayeu i'sjde'sire l ioint y effected f'rointwo po tsiri tljie lempmircuitg Onefo'f'the conte 'ct poiritscontrolling the actuation of the supervisory signalis controlled bythe opera:

tor. The othericont'act' which controls the eigehaiige slysteriislin, which a central ource Iia ngourrfents"toellithelines'terminating at supervisory signeling i circuit is trolledby the subscriber; v desirable in supervisory signaling arr nge necessity of thirdjcontects of the spring}; 2 jacks and correspbnding' third contacts of ithe cord connecting-plugs, I r

7AB P V 'Y ys e o us i o lrij fiic fi With a two-wire jacksystem has been pro} p0'sed,in Whi' trolled by the operativecondition of the sub:

seribers substation apparatus. Such e su pervl'sory signaling, arrangement is ore. or

less" complicated end requires for e'aeh. sup er visoryfll'amp ors gnal tvvo relays, orat le'e'st' It ha b en. foiled.

h 1M i uminel h fi r l itl has been jointly cont'rolledby two'rel'aygone line-jalclgwhile weather rel ayh asvbeen con;-

merits of this class to, if possible, evoldvtliel three relays for 'two'supervisorylampsf These relays are expensive to install end, are liable to get out of order end edjustrnentf; They do, however, introduce theedvantege of pij'oi-z viding' en inductively-b silenced, ,Qircuit, there being in such an installation ail-impedance,

between the terminals of the common battery. 7 v

i and eitherside of'the teleiPhone-cirduit which transmits voice-currents. H W v v Itiis the purpose of my presentziiivention to provide a double supervisory signaling: sys

tern employing" small electric lamps es sig; ne'ls in which there'need be but onejrelay for anced circuit my present'inventionshoivsalii,

improvement over the supervisory signaling sy'stemdiselosed inPetent No. 6 88,l 5 f2' i s-' sued to me December 10, 1901. In pres;

the associated plug-ins line-jack, end' seg ond'ly,'by a relay connected between a ter'rifi: na'lof the common batteryand'on'e ,of' cord-strands, the ,ene'rgizationiof the' releyi being controlled by the operative condition each lempand' in which, furthermore, the

exit system e'a ch'supervisory lamp is" jointly controlled, first, directly by the insertionpf Ioo of the substation apparatus associated with the line within which the plug has been inserted.

The features of my invention will be more clearly understood by reference to the accompanying drawing, wherein I have shown at each of the subscribers substations A and B the usual substation apparatus for common-battery systems, which comprises in each instance a hook-switch 1, which when in its normal depressed condition, due to the weight of the receiver 2, serves to connect the line-limbs 3 and 4 through a call-bell 5 and the condenser 6. When in its upper position, due to the removal of the receiver 2, the hook-switch closes a circuit through the battery-transmitter 7 and the primary 8 of an induction-coil whose secondary 9 is serially connected with the receiver 2. The line-circuit arrangement herein shown is similar to that disclosed in my above-mentioned patent. It will be apparent, however, to those skilled in the art that any other line-circuit maybe employed.

The line-limb 4 leads through the winding 10 of a differential cut-off relay 1 1, and thence to the negative grounded pole of the common battery 12. The line-limb 3'leads to the armature 13 of the relay 11, this armature normally making connection with its back contact 14, which is connected through the other winding 15 of the differential cutoff relay, and thence through the line-signal 16 to the positive pole of the common battery 12. The armature 13 is provided with a front contact 17, which leads to the sleevecontacts 18 18 of the line-jacks 19 19. The tip-contacts 20 20 of the line-jacks are connected directly with the line-limb 4, as shown. The windings 10 and 15 of the cut-off relay are differentially wound in order that the passage of equal currents through both windings at the same time will cause no net energization of the relay-core.

The operators cord-connecting apparatus comprises the answering-plug 21 and the call ing-plug 22. The tip-contacts of these plugs are connected by the tip-strand 23, while the sleeve-contacts are connected by means of the sleeve-strand 24. The usual operators listening-key 25 is provided, an actuation of which serves to connect the operators tele phone set 26 in bridge of the cord-strand. A ringing-key 27 is also provided, an actuation of this key serving to connect the terminals of the ringing-generator 28 in bridge of the cord-strands leading to the calling-plug and to break the connection to the answeringplug. The conductive continuity of the sleeve-strand is interrupted by the serial inclusion of a condenser 29, this condenser, however, readily permitting the passage of telephonic voice-currents. There are per manently connected between the positive 65 pole of the common battery 12 and the conductively-insulated portions of the sleeve* strand 24 supervisory relays 30 and 31. The supervisory lamps or signals 32 and 33 are connected, one between the tip-strand leading to the answering-plug and the back contact 34 of the armature 35 of the relay 30 and the other between the tip-cord strand leading to the calling-plug 22 and the back contact 36 of the armature 37 of the relay 3]. There is included in each of the lamp-circuits an impedance-coil, that associated with the lamp 32 being designated as 38 and that associated with the lamp 33 as 39.

The operation of such a system may be described as follows: A subscriber at substation A desiring connection with some other subscriber removes the receiver 2 from the telephone-switch hook, thereby closin a conductive circuit between the line-hm s 3 and 4, leading to substation A. The circuit thus closed may be traced as follows: from the positive pole of the common battery 12, through the line-signal 16, the winding 15 of the differential cut-off relay, contact 14, armature 13, line-limb 3, transmitter 7, primary Winding 8, switch-hook 1, line-limb 4, winding 10 of the differential cut-ofl' relay, and thence to the negative pole of the com mon battery 12. The closure of this circuit causes an actuation of the line-signal 1 6 to indicate to the central-station operator that a connection is desired. The cut-off relay 11, however, is not actuated,for the reason that its two windings are differentially connected and no net energization is produced by the closure of a circuit through these two windings. The operator answers the signal produced by inserting the answering-plu 21 within the answering-jack of the callingine. A circuit is thereupon closed. through the supervisory signaling-lamp as follows: from the positive pole of the battery 12, through the armature 35, its back contact 34, the lam 32, impedance-coil 38, the tip-contact of t e plug 21, the tip-spring 20, winding 10 of the cut-off relay 11, and thence to the negative ole of the common battery. The closure 0 this circuit would cause an illumination of the lamp 32, except for the fact that the relay 30 is at the same time energized. This relay 30 is energized over the following circuit: from the positive pole of the battery 12, through the winding of the relay 30, the

sleeve-strand 24, leading to the sleeve-con tact of the plug 21, sleeve-contact 18 of the jack 19, contact 17, armature 13, line-limb 3 transmitter 7, primary 8, switch-hook 1, linelimb 4, winding 10 of the differential relay, and thus to the grounded negative pole of the common battery 12. The energization of the relay 30 due to the flow of current over this circuit causes an attraction of the armature 35, whereupon the circuit through the lamp 32 is broken. A momentary circuit, however, does flow through the lamp 32 this circuit being. traced, as previously stated,

through the winding 10' of the differential cut-offrelay. The path of increased resistance through thewin'ding 10 of the differential cut-01f relay afforded by the circuit through the supervisory lamp 32 causes an uni-balancing of the energization of the differential relay due to the two windings, and the magnetization due to the current flowing through winding 10 overcomes that due to the current flowing throughwinding 1-5, and a net energization of the cut-off relay is produced to attract the armature 13-, thereby cutting oil theiine-signal- 16; The operator now converses with the calling-subscriber toascertain the number of the subscriber to be called. Upon learning the number of the called subscriberthe operator inserts the callinglug 22 within a jack 19, associated with the ine leading to substation B-that is, as-

suming. thatsubstation B isthe station de-' sired by the calling-subscriber. It will be seen that after the calling-subscribers call has been answered by the insertion of the an- 'swering-plug 21 into an answering-j ack there will be an unbalanced condition of the circuit, which would cause induction disturbances, and therefore noise in the receiver of the calling-subscriber, due tothe path afforded from the positive pole of the common battery 12 through the armature 37, the con-' tact 36, lamp 33, and thence to the tip-strand- 23 of the operators cord-connecting apparatus, and from the tip-strand to the tip-spring 20, which is associated with line-limb 4, leading to substation A. This direct connection of a pole of the battery with aline-limb leading to substation A would cause noise, due to inductive disturbances. In order to prevent this noise, due to inductive disturbances and unbalancing of the line, the impedance 39 is included in circuit with the lamp 33. This with the line to substation B to the negative pole of the common battery 12. Theflow of current over this circuit causes an energization of the relay 11, whereby the armature 13 is attracted to'at once cut off the line-signal 16. The subscriber at substation B answers the call by removing his receiver from the switch-hook, whereby a conductive circuit is closed through the substation apparatus at B. The closure of this circuit causes, as in the case of the calling-line, the closure of a by breaking t cut-off relays.

circuit through the relay 31, whereby its ar mature 37 isattracted to break the circuit throu h the supervisory si naling-lamp 33. It will be seen that eachsu scriber controls one of the supervisory relays 30"or 31 and that each subscriber in this manner has complete control and supervision of one of the suervisory signaling-lamps. It will of course I a; i

be understood that when both of-the supervisory relays 30 and 31 are energized, and the circuits through both of L the supervisory lamps32 and 33 are, thereby broken, there will be noneed for the impedances 38 and 39 to balance the telephonic circuit inductively;

but these impedances serve to prevent noise j due to inductive disturbances whenever a single plug of the cord-connecting apparatus is inserted in a jack. Upon the completion of the conversation 'the'subscribers re lace their receivers u on the switch-hooks, t erehe conductive line-circuit, whereupon the supervisory relays 30 and 31, ;are den'ergi'zed to permit the retraction of their armatures'. The armatures when in their retracted normal position close circuits through the supervisory lam s and impe dances 38 and 39 to cause the i lumination of the supervisory lamps, thereby notifying the i operator of the desired disconnection. The operator upon receiving the disconnect signal from either one or both of the substations" removes the associated plug or lugs, thereby breaking the circuit through t e difierential Upon the denergization of the cut-off relays the armatures 1-3 are retracted to restore the line circuits to their normal condition.

While I have shown my improved super-- visory signaling system in connection with a certain line-circuit,it will be apparent to those skilled in the art that many other line-circuits may-be employed with equal advantage, and inthe same way the cord-circuit maybe modified in a great many ways. I-

-do not wish, therefore, to limit myself to the precise construction and circuit arrangefments herein set forth but,

Having described my invention, I claim as new and desire'to secure by Letters Patent 1. In a telephone exchange system, the combination with a telephone-line extending from a substation .to an exchange, of cord connecting apparatus for connecting said line with'another for conversation, a common source of current at the central exchange for supplying talking and signaling current to the cord-circuit and telephone-lines, a circuit extending between one pole of said source of' current and one cord-strand and including a supervisory lamp and an impedance-coil, a second circuit extending from thesame pole of said source'tothe other cord-strand and including only the winding of a supervisory relay, connectionof said cord-circuit with a telephone-line causing the circuit through said supervisory lamp to be completed, and actuation of substation apparatus upon connection of the cord-circuit with the line causing the circuit through the supervisory relay to be completed and the circuit through the supervisory lamp opened.

2. In a telephone-exchange system, the combination with a telephone-line extending by its limbs from a substation to an exchange, of cord connecting apparatus for connecting said line with another for conversation, a common source of current at the central exchange for supplying talking and signaling current to the cord-circuit and to the telephone-lines, a line-signal normally included in circuit with a telephone-line and said source of current upon actuation of substation apparatus, a circuit at the central exchange extending from one pole of said source of current to one cord-strand and including a switch, a supervisory lamp and a coil of high impedance, connection of said cord connecting apparatus with the line causing the line-signal to become inactive and causing'said circuit to become closed,whereby the supervisory lamp becomes illuminated, and a second circuit at the exchange connected between the same pole of said source and the other cord-strand, said circuit containing only the winding of a supervisory relay controlling said switch, actuation of substation apparatus upon connection of the cord-circuit with the line causing closure of said circuit through said supervisory relay, whereby said switch is actuated to open the supervisory-lamp-containing circuit.

3. In a telephone-exchange system, the combination with a telephone-line extending from a central exchange to a substation, of cord connecting apparatus at the central exchange for connecting telephone-lines to- Y gether, a common source of current at the exchange for supplying talking and signaling current to the cord-circuit apparatus and to the telephone-line, each line-limb being normally connected with one pole of said source and each including one of the difierential windings of a cut-off relay, a line-signal in-' cluded in one of said line-limbs and normally connected with the line-limb through the armature of said cut-oil relay, spring-jacks having one contact permanently connected with one line-limb and another contact normally disconnected from the other line-limb, a circuit extending from one pole of said source to one cord-strand and including a switch, supervisory lamp, and a coil of high impedance, connection of said cord-circuit with a spring-jack causing closure of the su pervisory-lamp circuit and energization of the cutoii relay, whereby the line-signal is removed from circuit and the normally disconnected spring-jack contacts connected with the line limb, a second circuit extending from the same pole of said source to the other cord-strand, and a supervisory relay in said second circuit and controlling said switch, actuation of substation apparatus upon connection of the cord-circuit with the line causing closure of said second circuit whereby the supervisory relay becomes energized to actuate said switch to open the supervisory lampcircuit.

4. In a telephone-exchange system, the combination with a telephone-line extending from a substation to the exchange, of a cordcircuit for connecting said line with another for conversation, a common source of current at the exchange for supplying talking and signaling currents to the cord-circuit and telephone-line, a supervisory lamp-circuit extending between one pole of said source and one cord-strand, and a winding of high impedance included in said supervisory circuit, said impedance being included in circuit only when the substation apparatus is inactive but disconnected from any circuit upon actuation of the substation apparatus.

In witness whereof I hereunto subscribe my name this 25th day of August, A. D1903.

HARRY G. WEBSTER.

Witnesses:

HARvEY L. HANsoN, JOHN STAHR. 

